Usefold provides functionality to ease putting fold markers based
on indentation when using the marker foldmethod. No maps are
provided by default but has to be set up by the user.

Usefold_FoldDown / FoldUp / FromInside functions are provided
and creates a fold between the current line and the first line
below/above that has the same level of indentation. In the last
case, FoldDown is called on the first line above the current
that is indented less than the current line.
The functions can also be given a parameter, to specify another
line than the current.

Usefold_foldtext is also provided and is (according to me, the author)
a better foldtext, that among other things preserve indentation.